Inertia responsive switch



March 14, 1961 R. Luclr-:N

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United States Patent O 2,975,248 INERTIA RESPONSIVE SWITCH Rene Lucien, Neuilly-sur-Seine, France Filed Nov. 13, 1958, Ser. No. 773,717 Claims priority, application France July 21, 1958 12 Claims. (Cl. 200-61.46)

This invention relates to inertia responsive switches.

My earlier patent, No. 2,840,715, describes a device of the type comprising an inertia ily-wheel elastically mounted on a shaft driven into rotation by the wheel of a vehicle and capable of being angularly rotated about said shaft when the wheel, under braking action, reaches excessive deceration tending to block the wheel, said displacement being used to close or open an electric circuit which includes an electrovalve controlling a wheel brake actuated by hydraulic pressure.

The present addition relates to an industrial embodiment, especially suitable for automotive vehicles, of the above-indicated type of device, especially adapted to facilitate large-scale production of this device and to make it so resistant to wear and tear that it is capable of operating, without maintenance or repair, for at least the same period of time as the vehicle -on which it is to be mounted.

A prototype constructed in accordance with the invention and subjected to endurance tests corresponding to a 100,00() km. drive, under rigorous conditions of frequent and abrupt braking, not only failed to show any operating defect, but, having been disnrounted, showed no sign of Wear and tear which might have interfered withits proper functioning in its foreseeable future.

The invention consists of various improvements in construction which will be described below and which will be illustrated by the accompanying drawing in which, to facilitate matters, the members corresponding to similar members in the rnain application are given the same reference characters.

Fig. 1 is an axial cross section of the device;

Fig. 2 is a diagrammatic view of said section in perspective.

A first improvement is that the shaft 2 driven into rotation by the wheel of the associated vehicle is supported by two ball bearings 40 and 41 centered on the axis of the casing, ball bearing 40 being supported by a bearing 3 of the casing and ball bearing 41 being supported by a bearing 42 formed in the closure plate 6 which is conductive. By substituting rolling friction for sliding friction, practically all wear and tear is eliminated.

The inertia fly-wheel 18 is mounted on two ball bearings 17 which allow it an angular displacement relative to the shaft 2 aided in one direction and opposed in the other by the prestressed spring 24. The inner end of said spring is engaged in a slot 43 arranged in an extension 44 of the iiy-wheel 18 `and its outer end 45 is wound up about itself (Fig. 2) and housed in a cylindrical cavity 46 bored into a cylindrical ring 47. The latter is engaged in a plate 48 integral with the shaft 2. The ring 47 is capable of rotating in the plate 48 and of being immobilized in the latter by a set screw 49. This makes it possible to impart to the spring, depending on the angular position of the ring in the plate, a predetermined stress for a given relative angular position of the ily-Wheel 18 and plate 48. Said position is determined by the contact of two stops (not shown) supported respectively by the flywheel and the plate. This is the angular position shown in Figs. 1 and 2.

has not reached an undesirable deceleration,

2,975,248 Patented Mar. 14, 1961 The shaft 2 is provided with grooves 50 over a portion of its length, and an insulating member 11 is molded on and around said portion; the member 11 is surrounded with a sleeve 51 on which a conducting disc 12 is centered. Said disc is split along a radius, and a screw 14 locks the disc 12 on the sleeve 51, so that the disc 12 is locked on the insulating member 11.

The disc 12 carries a contact piece or stud 38 which exerts pressure on the fly-wheel 18. In the position shown in the figures, the contact piece 38 bears against an insulating block 52 embedded in the fly-wheel 18, and which is level with the plane surface of the latter against which the conducting stud rubs.

An insulating cup or dish 53 is fixed in the casing 1 and serves as housing for a conducting member 54. The cup 53 also houses a conducting member 55. Said piece 54 is provided with radial grooves 56 for carbon brushes 57 urged inwardly by springs 58. Said carbon brushes rub against the sleeve 51 which behaves like a collector.

In the same manner, a stud 59 made of tungsten or tungsten frit, the end of which is convex, is housed in an axial cavity in the shaft 2 and is urged against a steel stop 60 of the bearing 42 by a spring 61. The press-stud may equally well be made of steel and the stop made of tungn sten.-

A terminal 62 insulated from the plate 6 by an insulating ring 63 is -screwed through the plate 55 into the piece 54. Another terminal 64 is xed to the plate 6. Two seals 65 have the purpose of preventing dust formed by the worn carbon brushes from spreading in the device where the dust might cause short-circuits, especially when settling on the insulating block 52 of the y-wheel.

In the example shown in the drawing, the shaft 2 is driven into rotation by means of a gear wheel 66 iirmly connected to the shaft by a pin 67. The gear Wheel is driven by a chain drive-n, in turn, by any member caused to rotate by the wheel. The invention is, however, not limited to this method of drive.

The device operates as follows: as long as the wheel the shaft 2 and the inertia fly-wheel 18 rotate together and remain in the relative positions shown in the figures. Electric current at the terminal 62, and which would be transmitted through the insulating member 54, the carbon brushes 57, the collector 51, the member 12 and the stud 38, is interrupted by the insulating block 52. lf, on the other hand, the deceleration of the wheel and, consequently, of the shaft 2 exceeds the limit at which the inertia of the iiywheel prevails over the pre-stressed force of the spring, the fly-wheel is displaced angularly with respect to the shaft 2 and, consequently, with respect to the member 12. The contact piece 38 leaves the insulating block 52 and current passes through the fly-wheel 18, the spring 24, the ring 47, the shaft 2, the spring 61, the press-stud 59, and the end stop 60 to the terminal 64 which is grounded. The solenoid of the electro-valve (not shown) is then excited. The valve thereby causes the hydraulic pressure circuit to communicate with the reservoirs. The pressure drops in the pressure cylinder of the brake which becomes inoperative. The brakes become operative again when the deceleration has decreased and so on, as long as the braking action imparts excessive deceleration to the wheel.

As can be seen, the invention employs a metal-on-metal friction at the member 12 for purposes of current transmission, as well as carbon-on-metal friction by means of the carbon brushes 57 engaging the collector 51. The radial arrangement of the carbon brushes permits making them very long and, consequently, they have a long useful life before they are fully used. Since they rub against a collector of relatively small diameter, the tangential velocity and, consequently, wear and tear are low.

The function of supporting the shaft 2 is performed by a shaft rotatable in ball bearings 40 and 41, and an electric conductor function is now effected by the tungsten press-stud 59. The life of the contact is thus lengthened considerably. This avoids the use of steel balls'used as current conductors, which ballsA are damaged rather quickly by the passing of the current.

Attention is also directed tothe structure associated with the insulating block 52. f Tests have shown that this structure is capable of increasing the resistance to wear of this circuit-breaker arrangement' which must operate many times with each braking action..

Fig. 1 shows a second insulating block 52a diametricallyopposite block 52. This is a reserve stud which is normally non-operative, since the amplitude of the oscillations of the fly-wheel do not reach 180. In case block 52 is prematurely worn, the member 12 is shifted 180 about its axis by loosening and then tightening the screw 14, thereby causing the contact piece 38 to cooperate with the insulating block 52a. Owing to this precaution, it is possible to replace the worn block in very little time and Without the need to use spare parts.

The use of plate 48 integral with the shaft is advantageous for mass production, since this arrangement c-an, for example, be pressure molded and thus be produced more economically.

There will now be obvious to those skilled in the art many modifications and variations of the methods, structures and apparatus set forth above. These modifications and variations will not, however, depart from the spirit of the invention as defined in the following claims.

What is claimed is:

1. An inertia responsive apparatus comprising a casing, the casing, an inertia responsive switch on and electrically connected with the shaft said switch including a member extending along but electrically isolated from said shaft, at least one brush radially disposed with respect to and frictionally and electrically engaging said member, a ball bearing on the casing and supporting the shaft for rotation, a terminal device on the casing coaxially disposed with respect to the shaft, and a springloaded plunger device in an end of the shaft and coaxial therewith for engagingthe terminal device to provide an electrical circuit between the terminal device and switch.

2. An inertia responsive apparatus as claimed in claim 1 wherein one of the devices is of tungsten and the other of the devices of steel.

3. An inertia responsive switch comprising a shaft, a fly-wheel rotatable on the shaft and including electrically conductive and insulating portions, means fixed on the shaft for rotation therewith and for selectively engaging the conductive and insulating portions depending upon the relative rotational displacement between the shaft and fly-wheel, a spring coupling the fly-wheel and shaft for relating the rotation thereof, and means operatively associated with the spring for adjusting the tension thereof and thereby the coupling of the fly-wheel to the shaft, said spring being a spiral spring centered on the shaft and said means comprising a collar on the shaft and engaging an end of the spring and a set screw for adjustably fixing the collar on the shaft, the other end of the spring being connected to the y-wheel.

ductive sections one of which is electrically coupled to the `shaft and the other of which is insulated therefrom, an electrically conductive sleeve on said other section concentric with the shaft and rotatable therewith, a second electrically conductive terminal on the casing, and at least one brush coupled to said second terminal and frctionally engaging said sleeve, said brush being radially disposed with respect to` said sleeve and shaft.

5. Apparatus as claimed in claim 4 wherein said brush is of carbon.

6. Apparatus as claimed in claim 5 comprising sealing A members on the casing and in engagement with said sleeve for isolating the brush and confining waste therefrom.

7. An inertia responsive switch comprising a driven shaft, a fly-wheel rotatable on the shaft and having a surface normal to the latter, a coupling spring coupling the y-wheel to the shaft whereby said y-wheel is driven by the shaft, an insulating block in the fly-wheel and having a surface substantially coplanar with the first said surface, the surface of said block being spaced from the shaft, said shaft, ily-wheel and spring being electrically conductive elements, an electrically conductive disc fixed to the shaft for rotation therewith and in axially spaced relation to said surfaces, the disc being electrically insulated from the shaft, an electrically conductive stud on the disc and in selective frictional engagement with the surfaces, and a source of electrical power coupled to said disc and shaft between which electrical continuity is controlled by selective engagement of the stud with said block and said fly-wheel in response to displacement of the latter on said shaft.

8. A switch as claimed in claim 7 comprising ball bearings on the casing supporting the shaft for rotation.

9. A switch as claimed in claim 8 wherein said source comprises spaced and insulated terminals on the casing, one of the terminals being coaxially disposed relative to said shaft, comprising a spring loaded plunger in an end of the shaft for engaging the coaxial terminal.

l0. A switch as claimed in claim 9 comprising a sleeve on said disc and concentric with the shaft, and brushes on the casing coupled to the other of said terminals for frictionally engaging said sleeve.

1l. A switch as claimed in claim l0 comprising means coupled to said coupling spring for adjusting the tension thereof and thereby the coupling of the ily-wheel with the shaft. t

12. A switch as claimed in claim 11 comprising a further insulating block in the y-wheel and diametrically opposite the first said block for replacement purposes.

References Cited in the tile of this patent UNITED STATES PATENTS Lucien June 24, 1958 

